How to add a progress bar

I have a web application that has a download button. This button is intended to download a csv file.

The application works fine but I have nothing that can show the user that the process is being downloaded (like a progress bar).

I have tried to incorporate several forms but nothing works for me.

What would be the best way to proceed?

This is my photon on the .aspx page:

            <asp:ScriptManager ID="ScriptManager1" runat="server">
</asp:ScriptManager>
<asp:UpdateProgress ID="updProgress"
AssociatedUpdatePanelID="UpdatePanel1"
runat="server">
    <ProgressTemplate>           
    <center></center><img alt="progress" src="img/loader.gif"/>
       Processing...           
     </center>
    </ProgressTemplate>
</asp:UpdateProgress>


        <asp:UpdatePanel ID="UpdatePanel1" runat="server">
    <ContentTemplate>

           <center><asp:Button ID="Button3" runat="server" Text="Download" OnTextChanged="Download" Height="60" 
                  Width="160" Font-Size="16" ForeColor="Black" BackColor="#C6D5E2" BorderStyle="Groove" OnClick="Download"/></center>
                <br />
 </ContentTemplate>
</asp:UpdatePanel> 

My problem is the following when trying to incorporate the solution that I mention.

The progress bar appears fine, but disappears several seconds before the process ends.

When using this solution, the file is not downloaded and the process is stopped.